As long as the trip is at least one week away, travelers can cancel ordinary tickets on Allegiant Airlines for a full refund within 24 hours of placing the reservation. Should you not have Trip Flex, you can cancel for a fee (about $75 per segment) and receive a travel credit for the balance. Cash refunds are infrequent because the majority of fares are non-refundable. Changes and cancellations are free of charge when using Trip Flex. You can handle cancellations at the airport, online, or through customer service.